The objectives of this research plan are to clarify the relationships among endocrine, paracrine, and cellular events which culminate in parturition in primates. Aim 1 will establish the separate effects of exogenous ACTH or CRH administered to the fetus or mother at 80+ percent gestation in terms of inducing premature labor as well as describe the changes in the endogenous levels of the same hormones. Aim 2 will describe the presence of androgen and glucocorticoid receptors (ARs, GRs) in rhesus amnion, chorion, decidua, and myometrium at 80 and 100 percent of gestation using immunohistochemistry and ribonuclease protection assay of receptor mRNA. A second part of Aim 2 will use maternal/fetal infusion of androgen agonists and antagonists and a 5-alpha reductase inhibitor to determine the effects of alterations of maternal/fetal androgen levels on gestational length. Aim 3 examines possible mechanisms of progesterone withdrawal by testing for a switch between myometrial progesterone receptor (PR) subtypes (A&B) near term, or a non-genomic mechanism of reduced amniochorion calcium mobilization ("membrane effects") in immune cells. Aim 4 will determine the effects of intraamniotic administration of human IL-8 on parturition.